Magnetostrictive member and method for manufacturing magnetostrictive member

Abstract

Provided is a magnetostrictive member having a high parallel magnetostriction amount and a small variation in the parallel magnetostriction amount between members, the magnetostrictive member having a high device output and suppressed variation in the optimal magnetic field strength in device characteristics when assembled in a magnetostrictive vibration power generation device. A plurality of magnetostrictive members are obtained from the same crystal, each magnetostrictive member is composed of a crystal of an iron-based alloy having magnetostrictive characteristics, and is a plate-shaped body having a long-side direction and a short-side direction, and the front surface and / or the back surface of the plate-shaped body has a plurality of grooves extending in the long-side direction. The ratio (standard deviation / average value) of the standard deviation of the optimal magnetic field strength obtained by electromechanical equivalent circuit analysis of the plurality of magnetostrictive members to the average value of the optimal magnetic field strength is 0.2 or less.

Description

Technical Field

[0001] This invention relates to magnetostrictive components and methods for manufacturing magnetostrictive components. Background Technology

[0002] Magnetostrictive materials have attracted attention as functional materials. For example, Fe-Ga alloys, as iron-based alloys, exhibit both magnetostrictive and inverse magnetostrictive effects, displaying large magnetostrictions of approximately 100–350 ppm. Therefore, in recent years, they have garnered attention as materials for vibration-driven power generation in the field of energy harvesting, with anticipated applications in wearable devices, sensors, and the like. As a method for manufacturing single crystals of Fe-Ga alloys, a method for growing single crystals using the Czochralski method (hereinafter referred to as the "Cz method") is known (e.g., Patent Document 1). In addition to the Cz method, manufacturing methods other than the Cz method include the vertical Bridgman process (VB method) and the vertical temperature gradient solidification method (VGF method) (e.g., Patent Documents 2 and 3).

[0003] Fe-Ga alloys in crystals <100> It has an easily magnetized axis in its orientation, enabling large magnetostriction in that orientation. Previously, magnetostrictive components of Fe-Ga alloys were developed by transferring magnetostrictive elements from Fe-Ga polycrystalline materials along this orientation. <100> Orientation can be achieved by cutting the oriented single-crystal portion into the desired size (e.g., non-patent document 1). However, crystal orientation has a significant impact on magnetostrictive properties. Therefore, it is considered that the direction of magnetostriction required for the magnetostrictive component should be maximally aligned with the magnetostriction of the crystal. <100> Single crystals with consistent orientation are the best material for magnetostrictive components.

[0004] Fe-Ga alloy single crystals relative to single crystals <100> When a magnetic field is applied parallel to the orientation, positive magnetostriction occurs (hereinafter referred to as "parallel magnetostriction"). On the other hand, when relative to... <100> When a magnetic field is applied perpendicularly, negative magnetostriction occurs (hereinafter referred to as "perpendicular magnetostriction"). As the strength of the applied magnetic field gradually increases, either the parallel or perpendicular magnetostriction saturates. The magnetostriction constant (3 / 2λ) 100 The difference between the saturated parallel magnetostriction and the saturated perpendicular magnetostriction is determined by the following formula (A) (e.g., Patent Document 4, Non-Patent Document 2).

[0005] 3 / 2λ 100 =ε( / / )― ε(⊥) ･･･Formula (A) 3 / 2λ 100 Magnetostriction constant ε ( / / ): relative to <100> Parallel magnetostriction when a magnetic field is applied in a parallel direction and the magnetostriction saturates ε(⊥): relative to <100> Vertical magnetostriction when a magnetic field is applied perpendicularly and the magnetostriction saturates The magnetostrictive properties of Fe-Ga alloys are considered to influence the magnetostrictive / inverse magnetostrictive effects and the characteristics of magnetostrictive vibration power generation devices, making them an important parameter in device design (e.g., Non-Patent Literature 4). In particular, it is known that the magnetostrictive constant depends on the Ga composition of the Fe-Ga alloy single crystal, becoming extremely large when the Ga composition is 18–19 at% and 27–28 at% (e.g., Non-Patent Literature 2), making Fe-Ga alloys with such Ga concentrations preferred for device use. Furthermore, in recent years, it has been reported that, in addition to a large magnetostrictive constant, a greater parallel magnetostriction also tends to result in higher device characteristics such as output voltage (e.g., Non-Patent Literature 3).

[0006] Magnetostrictive vibration power generation devices, for example, consist of an Fe-Ga magnetostrictive member wound around a coil, a magnetic yoke, and a permanent magnet for excitation (e.g., Patent Document 5, Non-Patent Document 4). In this magnetostrictive vibration power generation device, the structure is such that if the magnetic yoke of the movable part of the device vibrates, the Fe-Ga magnetostrictive member fixed to the center of the magnetic yoke vibrates in conjunction. Through the inverse magnetostrictive effect, the magnetic flux density of the coil wound around the Fe-Ga magnetostrictive member changes, generating an electromagnetic induction electromotive force and thus producing electricity. In the magnetostrictive vibration power generation device, vibration is caused by applying a force along the long side of the magnetic yoke; therefore, the Fe-Ga magnetostrictive member used in the device is preferably a readily magnetized axis. <100> Processing is carried out in a way that makes the long side the same.

[0007] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2016-28831 Patent Document 2: Japanese Patent Application Publication No. 2016-138028 Patent Document 3: Japanese Patent Application Publication No. 4-108699 Patent Document 4: Japanese Patent Publication No. 2015-517024 Patent Document 5: International Publication No. 2011 / 158473 Patent Document 6: International Publication No. 2021 / 100467 Patent Document 7: Japanese Patent Application Publication No. 2020-63997 Non-patent literature Non-patent document 1: Etrema Corporation, State of the Art of Galfenol Processing. Non-patent literature 2: AE Clark et al., Appl. Phys. 93(2003)8621. Non-patent literature 3: Jung Jin Park, Suok-Min Na, Ganesh Raghunath, and Alison B. Flatau., AIP ADVANCES 6, 056221 (2016). Non-patent literature 4: Toshiyuki Ueno, Journal of the Institute of Precision Engineering, Vol. 79, No.4, (2013) 305-308. Non-patent document 5: Journal of the Marine Acoustics Society, Vol. 24, No. 3 (1997) Summary of the Invention The problem that the invention aims to solve The characteristics of magnetostrictive vibration power generation devices are influenced by the magnetostrictive properties of the magnetostrictive components. Therefore, these components are required to possess high magnetostrictive properties and small deviations in these properties. Specifically, it is assumed that the crystal orientation of the Fe-Ga alloy single crystal is... <100> If the Ga concentration is uniform, a magnetostrictive member with a uniform magnetostrictive constant can be obtained. However, as disclosed in Non-Patent Document 3, the device characteristics are affected not only by the magnetostrictive constant but also by the parallel magnetostriction. Therefore, Patent Document 6 discloses that by adding multiple grooves, such as grinding marks, extending along the long side of the magnetostrictive member, a magnetostrictive member with high magnetostrictive constant and parallel magnetostriction, and small deviations in magnetostrictive constant and parallel magnetostriction between members, can be obtained. When this magnetostrictive member is assembled into the magnetostrictive vibration power generation device and the device characteristics are verified, it can be confirmed that the predetermined device output (e.g., power generation such as force coefficient) is obtained, and the deviations in device output between devices are small.

[0008] However, to maximize the output (power generation) of the device, the magnetic flux density of the magnets assembled in the device needs to be appropriately set. Specifically, it needs to be set to a magnetic flux density approximately half the maximum parallel magnetostriction of the magnetostrictive material assembled in the device (hereinafter referred to as the optimal magnetic field strength).

[0009] In the magnetostrictive vibration power generation device that uses the magnetostrictive component of Patent Document 6, the deviation of the optimal magnetic field strength of the magnetostrictive material is large. In order to improve the output of the device, it is necessary to adjust the strength (magnetic flux density) of the magnet for each device, which leads to a decrease in productivity.

[0010] Therefore, the present invention aims to provide a magnetostrictive component with high parallel magnetostriction and small deviation of parallel magnetostriction between components, which, when assembled into the magnetostrictive vibration power generation device, results in a large device output and suppresses deviation of the optimal magnetic field strength, as well as a method for manufacturing the magnetostrictive component.

[0011] means for solving problems According to the present invention, a magnetostrictive member is provided, wherein the magnetostrictive member is a plurality of magnetostrictive members obtained from the same crystal, which is composed of a crystal of an iron-based alloy having magnetostrictive properties, and is a plate-shaped body having a long side direction and a short side direction. At least one of the surface and back side of the plate-shaped body has a plurality of grooves extending along the long side direction. The ratio of the standard deviation to the average value of the optimal magnetic field strength of the plurality of magnetostrictive members obtained by electromechanical equivalent circuit analysis (standard deviation / average value) is 0.2 or less.

[0012] Alternatively, the configuration may be such that the ratio of the standard deviation to the average value of the force coefficients obtained by electromechanical equivalent circuit analysis of the plurality of magnetostrictive members (standard deviation / average value) is 0.3 or less. Alternatively, the configuration may be such that the ratio of the standard deviation to the average value of the force coefficients obtained by electromechanical equivalent circuit analysis of the plurality of magnetostrictive members (standard deviation / average value) is 0.1 or less.

[0013] Additionally, a magnetostrictive member is provided, wherein multiple magnetostrictive members are obtained from the same crystal, and are composed of a crystal of an iron-based alloy having magnetostrictive properties. The member is a plate-shaped body having a long side and a short side. The ratio (standard deviation / average value) of the standard deviation of the optimal magnetic field strength obtained by electromechanical equivalent circuit analysis of the multiple magnetostrictive members to the average value of the optimal magnetic field strength is 0.2 or less, and the ratio (standard deviation / average value) of the standard deviation of the force coefficient obtained by electromechanical equivalent circuit analysis to the average value of the force coefficient is 0.3 or less. Alternatively, the plate-shaped body may have a thickness of 0.3 mm or more and 5 mm or less.

[0014] According to the present invention, a method for manufacturing a magnetostrictive member according to the above-described manner can be provided, wherein the method comprises: forming a plurality of grooves extending along the long side direction on at least one of the surface and back surface of a plate-shaped body composed of a crystal of an iron-based alloy having magnetostrictive properties and having a long side direction and a short side direction; and performing heat treatment on the plate-shaped body having the plurality of grooves extending along the long side direction.

[0015] Alternatively, the configuration may include forming the plurality of grooves by surface grinding. Alternatively, the configuration may include a heat treatment temperature of 400°C or higher and 700°C or lower. Alternatively, the configuration may include a heat treatment holding time of 5 hours or less. Alternatively, the configuration may further include forming a plurality of grooves extending along the long side on the plate-like body after heat treatment.

[0016] Invention Effects According to the present invention, a magnetostrictive component and a method for manufacturing the magnetostrictive vibration power generation device are provided, which, when using a magnetostrictive component with high parallel magnetostriction and small deviation of parallel magnetostriction between components, exhibits high device output and can suppress deviation of optimal magnetic field strength. Attached Figure Description

[0017] Figure 1 This is a diagram illustrating an example of a magnetostrictive member involved in an embodiment.

[0018] Figure 2 This is a graph illustrating an example of the change in the BH curve of a magnetostrictive component when stress is applied.

[0019] Figure 3 This is a diagram illustrating an example of an impedance measuring device.

[0020] Figure 4 This is a diagram showing the electromechanical equivalent circuit of the measuring coil.

[0021] Figure 5 This is a flowchart illustrating an example of a method for manufacturing a magnetostrictive component according to an embodiment.

[0022] Figure 6 This is a diagram showing examples of single crystals and thin-plate components.

[0023] Figure 7 This is a flowchart illustrating an example of a re-groove formation performed after heat treatment in the manufacturing method of the magnetostrictive member according to the embodiment. Detailed Implementation

[0024] The following description refers to the accompanying drawings. Furthermore, in each of the accompanying drawings, some or all portions are depicted schematically, with variations in scale.

[0025] [Implementation Method] The magnetostrictive member of this embodiment and the method for manufacturing the magnetostrictive member will be described below.

[0026] (Magnetostrictive component) First, the magnetostrictive member of this embodiment will be described. Figure 1 This is a diagram illustrating an example of a magnetostrictive member involved in an embodiment.

[0027] like Figure 1 As shown, the magnetostrictive member 1 is a plate-shaped body having a long side direction D1 and a short side direction D2. The plate-shaped body is preferably rectangular when viewed from above. The plate-shaped body has a surface (front) 3 and a back surface 4. The surface 3 and the back surface 4 are preferably parallel to each other, but they may also be non-parallel.

[0028] Magnetostrictive member 1 is composed of a crystal of an iron-based alloy. Multiple magnetostrictive members 1 are obtained from the same crystal. The iron-based alloy is only required to possess magnetostrictive properties and is not particularly limited. Magnetostrictive properties refer to the characteristic of producing a shape change when a magnetic field is applied. Examples of iron-based alloys include Fe-Ga, Fe-Ni, Fe-Al, Fe-Co, Tb-Fe, Tb-Dy-Fe, Sm-Fe, and Pd-Fe alloys. Alternatively, alloys containing a third component can also be used. For example, alloys containing Ba, Cu, etc., can be used in Fe-Ga alloys. Among these iron-based alloys, Fe-Ga alloys have a larger magnetostrictive property and are easier to process compared to other alloys, and are therefore used in vibration-powered energy harvesting materials, wearable terminals, and sensors. In the following description, as an example of magnetostrictive member 1, an example of a magnetostrictive member 1 composed of a single crystal of an Fe-Ga alloy will be explained.

[0029] Fe-Ga alloy single crystals have a body-centered cubic lattice structure, with the first of the directional indices in the Miller indices. <100> Axis to the third <100> Axis (reference) Figure 6 Equivalent to the first to third {100} surfaces in the Miller index (refer to...) Figure 6 The basic principle is that (100), (010), and (001) are equivalent. Furthermore, Fe-Ga alloys possess the property of causing large magnetostriction in specific crystal orientations. When utilizing this property in a magnetostrictive vibration power generation device, it is preferable to align the desired magnetostriction direction of the magnetostrictive member 1 with the orientation (direction) where the crystal's magnetostriction is maximized. Specifically, as described above, it is preferable to set the easy magnetization direction, i.e., the <100> direction, in the single crystal as the long side direction D1 of the magnetostrictive member 1. Setting the easy magnetization direction, i.e., the <100> direction, in the single crystal as the long side direction D1 of the magnetostrictive member 1 can be implemented, for example, by: analytically calculating the crystal orientation of the single crystal using known crystal orientations, and cutting the single crystal based on the calculated crystal orientation.

[0030] Furthermore, the crystal used in the magnetostrictive member 1 of this embodiment can be a single crystal or a polycrystalline crystal. To improve... <100> The orientation concentration of the crystal is more concentrated, which improves its properties as a magnetostrictive material. Compared with polycrystalline materials, using monocrystalline materials is advantageous. In addition, although polycrystalline materials have lower magnetostrictive properties compared with monocrystalline materials, they can be produced at a lower cost, so polycrystalline materials are sometimes used.

[0031] Magnetostrictive member 1 is used, for example, as a material (component) for vibration power generation devices in the field of energy harvesting, as well as for wearable terminals, sensors, and the like. For example, the magnetostrictive vibration power generation device shown in Patent Document 5 consists of a coil, a magnetostrictive member of an Fe-Ga alloy wound around the coil, a magnetic yoke, and a permanent magnet for excitation. This magnetostrictive vibration power generation device is structured such that when the magnetic yoke, which is the movable part of the device, vibrates, the magnetostrictive member fixed to the center of the magnetic yoke vibrates in conjunction, causing a change in the magnetic flux density of the coil wound around the magnetostrictive member through the inverse magnetostrictive effect, generating an electromagnetic induction electromotive force, thereby generating electricity. When used with such a structure, the magnetostrictive member 1 is plate-shaped, preferably a long, narrow rectangle when viewed from above. The thickness of the magnetostrictive member 1 is not particularly limited. For example, it is preferably 0.3 mm to 5 mm. The shape and size of the magnetostrictive member 1 are appropriately set according to the size of the intended device. For example, the length of one side of the magnetostrictive member 1 can be 5 mm or more, 10 mm or more, or 30 mm or more. For example, the size of the magnetostrictive member 1 can also be 16 mm in length (dimension) in the long side direction D1, 4 mm in width (dimension) in the short side direction D2, and 0.5 mm in thickness.

[0032] Furthermore, the shape and size of the magnetostrictive member 1 are not particularly limited. For example, the magnetostrictive member 1 may not be rectangular when viewed from above. For example, the shape of the magnetostrictive member 1 may be elliptical, racetrack-shaped, or irregular when viewed from above. In addition, when the shape of the magnetostrictive member 1 is not rectangular when viewed from above, the long side direction D1 can be the major axis direction, the major diameter direction, etc., and the short side direction D2 can be a direction orthogonal to the long side direction D1.

[0033] As described above, the inventors of this invention have confirmed that, as in Patent Document 6, by adding multiple grooves, such as grinding marks, extending along the long side of the magnetostrictive member, it is possible to obtain a magnetostrictive member with high magnetostriction constant and parallel magnetostriction, and small deviations in magnetostriction constant and parallel magnetostriction between members. However, it is known that in magnetostrictive vibration power generation devices using this magnetostrictive member, the deviation of the optimal magnetic field strength of the magnetostrictive member is large, requiring adjustment of the magnet strength corresponding to the deviation of the optimal magnetic field strength for each device, thus reducing productivity. Therefore, the inventors have discovered that by heat-treating the magnetostrictive member, the deviation of the optimal magnetic field strength can be reduced. Furthermore, the inventors of this invention have discovered that it is effective to evaluate the characteristics of the heat-treated magnetostrictive member using electromechanical equivalent circuit analysis. This invention was made based on the above insights.

[0034] Magnetostrictive components are used in magnetostrictive vibration power generation equipment; therefore, the principle of magnetostrictive vibration power generation is explained first. The easy magnetization axis of ferro-based magnetostrictive materials is

[100] , such as... Figure 2 As shown, if compressive stress is applied in the

[100] direction, the required magnetic field strength for magnetic field saturation increases; conversely, if tensile stress is applied in the

[100] direction, the required magnetic field strength for magnetic field saturation decreases. When a bias magnetic field is applied to the magnetostrictive material to continuously generate compressive and tensile stresses, the differential magnetic flux density of the BH curve changes. In magnetostrictive vibration power generation, this change in magnetic flux density is used to generate an alternating current in a coil covered with the magnetostrictive material through Faraday's electromagnetic induction.

[0035] exist Figure 2 In the absence of a magnetic field (magnetic field strength of 0 kA / m), the magnetic flux density remains near 0T during both compression and tension, resulting in no power generation. As the magnetic field strength increases, a difference in magnetic flux density occurs between compression and tension, enabling power generation. When the magnetic field strength becomes extremely high, magnetic field saturation occurs during both compression and tension, thus producing almost no difference in magnetic field strength and no power generation. Therefore, for efficient power generation, the magnetic field strength needs to be optimally applied to maximize the difference in magnetic flux density between compression and tension. In this specification, this optimal magnetic field strength is referred to as the optimal magnetic field strength.

[0036] In addition, as a method for evaluating the power generation characteristics of a magnetostrictive vibration power generation device, as disclosed in Patent Document 7 and Non-Patent Document 5 above, there is an evaluation method based on the analysis (impedance measurement) of electromechanical equivalent circuits.

[0037] The following explains the analytical (impedance measurement) method based on electromechanical equivalent circuits. Figure 3The diagram shows a general outline of the impedance measuring device. A bias magnetic field is generated in the excitation coil by a DC power supply, magnetizing the magnetostrictive material. With the magnetostrictive material placed inside the measuring coil, the impedance of the measuring coil is measured. The equivalent circuit of the measuring coil is as follows: Figure 4 The equivalent impedance of this circuit can be represented by the following equation (1). The force coefficient α is the coupling degree between the mechanical system and the electrical system, which is an indicator of the energy conversion efficiency from mechanical energy to electrical energy, and is positively correlated with the power output of the vibration power generation equipment.

[0038] [Number 1]

[0039] The circuit component is removed from the measured impedance loop and converted into a dynamic impedance loop. The force coefficient α is calculated according to the following equations (2) and (3).

[0040] [Number 2]

[0041] [Number 3]

[0042] While changing the bias magnetic field generated by the excitation coil by varying the current of the DC power supply, the impedance measurement described above is performed multiple times. When the force coefficient α is measured while varying the magnetic field strength from 0 kA / m to the saturation magnetic field, the force coefficient α is at its maximum near half the saturation magnetic field strength; otherwise, the force coefficient α decreases. The magnetic field strength at which the force coefficient α is maximum is the optimal magnetic field strength. The force coefficient α at the optimal magnetic field strength is defined as the force coefficient αmax (and sometimes simply referred to as the force coefficient). That is, by generating a bias magnetic field, magnetizing the magnetostrictive material, placing the magnetostrictive material inside the measuring coil, and repeatedly measuring the impedance of the measuring coil while changing the bias magnetic field to the saturation magnetic field strength, the characteristics of the magnetostrictive member, including the optimal magnetic field strength (where the force coefficient α is maximum) and the force coefficient αmax at the optimal magnetic field strength, can be determined.

[0043] The power generation characteristics of magnetostrictive materials can be evaluated using the force coefficient αmax, but the power generation characteristics decrease if the magnetic field strength deviates from the optimal magnetic field strength. That is, the force coefficient α depends on the applied magnetic field strength. Therefore, ideally, the bias magnet should be designed to achieve the optimal magnetic field strength within the power generation device, utilizing the force coefficient αmax. Thus, the optimal magnetic field strength is also an important performance indicator, requiring no deviation in each magnetostrictive material. Furthermore, a smaller optimal magnetic field strength allows for miniaturization of the bias magnet assembled in the power generation device, making it preferable from the perspective of miniaturization.

[0044] In the magnetostrictive member of this embodiment, the optimal magnetic field strength and the force coefficient αmax at the optimal magnetic field strength, obtained analytically based on the electromechanical equivalent circuit method described above, are used as indicators of the characteristics of the magnetostrictive member. The force coefficient αmax and the optimal magnetic field strength at the time of impedance measurement are used as indicators when impedance measurement is performed using the impedance measuring device described above. Thus, the evaluation is a narrow area where the strain gauge is attached in magnetostrictive measurement, but a wide area within the coil in impedance measurement, resulting in a better correlation with the power generation of the device. Furthermore, by making the shape of the measuring coil of the impedance clamp the same as the device, and the position where the magnetostrictive material is inserted into the measuring coil the same as the device, the correlation with the power generation of the device is further improved. In addition, the characteristics of the magnetostrictive member, including the force coefficient and the optimal magnetic field strength, can be evaluated with high accuracy. Furthermore, regarding impedance measurement, when the magnetostrictive member is used in a magnetostrictive vibration power generation device, the selection of the magnet and the output of the magnetostrictive vibration power generation device can be easily predicted.

[0045] The magnetostrictive member of this embodiment is characterized in that it is composed of a crystal of an iron-based alloy having magnetostrictive properties, and is a plate-shaped body having a long side direction and a short side direction. At least one of the surface and back surfaces of the plate-shaped body has a plurality of grooves extending along the long side direction. The ratio of the standard deviation to the average value of the optimal magnetic field strength (standard deviation / average value) of the magnetostrictive member is 0.2 or less, and the optimal magnetic field strength is calculated analytically using electromechanical equivalent circuits. A detailed description will follow.

[0046] like Figure 1As shown, at least one of the surface 3 and the back surface 4 (sometimes collectively referred to as the "surface and back surface") of the magnetostrictive member 1 in this embodiment has a plurality of grooves 2 extending along the long side direction D1. These grooves 2 extending along the long side direction D1 can, for example, be the same as those in Patent Document 6 described above. As shown in Patent Document 6, by forming a plurality of grooves 2 extending along the long side direction D1 on at least one of the surfaces of the magnetostrictive member, both the magnetostrictive constant and the parallel magnetostriction (also referred to as "modification of the magnetostrictive constant and the parallel magnetostriction") can be modified to a high level with small deviations between components, especially the parallel magnetostriction. Furthermore, in this embodiment, the extension of the plurality of grooves 2 along the long side direction D1 includes the case where the plurality of grooves 2 extend in a direction parallel to the long side direction D1, and the case where the plurality of grooves 2 extend in a direction intersecting the long side direction D1 at an angle of less than 40°.

[0047] As described above, it is known that by forming multiple grooves 2 on the surface of the magnetostrictive member as shown in Patent Document 6, the magnetostrictive constant and the amount of parallel magnetostriction are stable at a high level. The impedance measurement described above was performed using this magnetostrictive member, and it was found that the force coefficient is stable at a high level. For example, as shown in the embodiments described later, in Comparative Examples 1 and 2, the surface of the magnetostrictive member was a wire-machined surface (a surface obtained by slicing a single crystal ingot using a wire saw), and multiple grooves 2 were not formed. Examples 1 to 3 were magnetostrictive members with multiple grooves 2 formed on the surface of the magnetostrictive member. It is known that in the magnetostrictive members of these embodiments and comparative examples, the average force coefficient in Examples 1 to 4 (before heat treatment) was high and the deviation was small, exhibiting high stability. In contrast, in Comparative Examples 1 and 2 (before heat treatment), the average force coefficient was low and the deviation was large, making it unstable. It is speculated that this is due to the following reason: by forming multiple grooves on the surface of the magnetostrictive component, residual strain and other stresses are preferentially applied in the crystal in a direction orthogonal to the grooves due to the Thyman effect, the magnetic moments are uniformly rearranged, and the magnetostrictive properties are homogenized. However, it is known that the optimal magnetic field strength deviates in Examples 1-4 (before heat treatment). If the optimal magnetic field strength deviates due to the magnetostrictive member, then, as described above, in devices such as magnetostrictive vibration power generation, the strength of the magnet needs to be adjusted for each device, which reduces productivity. Therefore, in this invention, the deviation of the optimal magnetic field strength is suppressed by performing heat treatment with multiple grooves 2 formed on the surface of the magnetostrictive member. Details will be described later.

[0048] Regarding Examples 1-4, the deviation (standard deviation (σ)) of the optimal magnetic field strength after heat treatment is smaller compared to before heat treatment. The ratio of the deviation (standard deviation (σ)) of the optimal magnetic field strength before and after heat treatment (σ after heat treatment / σ before heat treatment) is less than 1.0, preferably 0.8 or less, more preferably 0.5 or less. Heat treatment has the effect of mitigating the internal stress of the magnetostrictive member. By forming multiple grooves 2 on the surface of the magnetostrictive member, residual strain and other stresses in a certain direction are applied within the crystal, and the magnetic moments are uniformly rearranged, thereby achieving a high level of parallel magnetostriction and force coefficient. However, the internal stress caused by crystal growth varies in each manufactured magnetostrictive member, which is considered to be the reason for the increased deviation of the optimal magnetic field strength. In the magnetostrictive member 1 of this embodiment, by performing heat treatment after forming multiple grooves 2 on the surface of the magnetostrictive member 1, residual strain and other stresses in a certain direction are simulated to mitigate and homogenize the internal stress, thereby obtaining a magnetostrictive member with stable high levels of parallel magnetostriction and force coefficient and a small deviation of the optimal magnetic field strength.

[0049] Furthermore, in this embodiment, the optimal magnetic field strength and force coefficient are affected by the width, length, and thickness of the magnetostrictive member due to the countermagnetic field. Therefore, in this embodiment, the evaluation was performed using the ratio (σ / AVE) of the deviation (standard deviation (σ)) of the optimal magnetic field strength to the average value (AVE). This evaluation can mitigate the influence of the width, length, and thickness of the magnetostrictive member at the optimal magnetic field strength.

[0050] In the magnetostrictive members of Examples 1-4 before heat treatment, the ratio of the deviation (standard deviation) to the average value (σ / AVE) of the optimal magnetic field strength is greater than 0.2. In contrast, after heat treatment, the ratio of the deviation (standard deviation) to the average value (σ / AVE) of the optimal magnetic field strength is 0.2 or less, preferably 0.18 or less, and more preferably 0.16 or less. Furthermore, the lower limit can be, for example, 0.01 or more. Although the average value of the optimal magnetic field strength of the magnetostrictive member varies depending on the width, length, and plate thickness of the magnetostrictive member, the ratio of the deviation to the average value of the optimal magnetic field strength (σ / AVE) is suppressed to 0.2 or less through heat treatment, indicating that the variation of the optimal magnetic field strength is significantly suppressed. It can be seen that in the magnetostrictive members shown in Examples 1-3, heat treatment can reduce the optimal magnetic field strength (average value) compared to before heat treatment. When the optimal magnetic field strength of the magnetostrictive member (magnetostrictive material) is high, a magnet with a high magnetic flux density is required. However, in the magnetostrictive members shown in Examples 1-3, the optimal magnetic field strength (average value) is lower than before heat treatment, thus reducing the magnetic flux density of the magnet used. For example, in the magnetostrictive member of this embodiment, the ratio before and after heat treatment (after heat treatment / before heat treatment) at the optimal magnetic field strength (average value) is 1.0 or less, preferably 0.8 or less. Furthermore, in the magnetostrictive member 1 of this embodiment, the average value of the optimal magnetic field strength (kA / m after heat treatment) is, for example, 1.0 or more, preferably 1.6 or more, and more preferably 2.0 or more.

[0051] Furthermore, the force coefficient remains unchanged before and after heat treatment, remaining stable at a high level. In the magnetostrictive member 1 of this embodiment, the ratio of the deviation (standard deviation) of the force coefficient (N / A) to the average value is 0.3 or less, preferably 0.1 or less. Moreover, its lower limit can be, for example, 0.001 or more. Additionally, in the magnetostrictive member 1 of this embodiment, the force coefficient (N / A) is, for example, 100 or more, preferably 140 or more, and more preferably 150 or more. Furthermore, in this embodiment, the force coefficient and the optimal magnetic field strength are values ​​calculated analytically using electromechanical equivalent circuits as described above, and can be obtained, for example, by the methods described in this specification.

[0052] Furthermore, the magnetostrictive member 1 of this embodiment may also be as shown in Examples 1 to 4, where the ratio of the deviation (standard deviation) of the optimal magnetic field strength to the average value of the optimal magnetic field strength (standard deviation / average value) is 0.2 or less, and the ratio of the deviation (standard deviation) of the force coefficient of the magnetostrictive member to the average value of the force coefficient (deviation / average value) is 0.3 or less. In addition, the lower limit may be, for example, 0.01 or more.

[0053] Furthermore, the aforementioned average values ​​and deviations (standard deviations) can be calculated based on multiple magnetostrictive components produced from the same crystal. For example, they can be calculated based on multiple magnetostrictive components manufactured from a single grown crystal under the same manufacturing conditions, or magnetostrictive components manufactured simultaneously under the same manufacturing conditions. Additionally, the number of measurements (n) is not limited regarding the number of magnetostrictive components produced from the same crystal, the calculation of the aforementioned average values ​​and deviations (standard deviations). The preferred number of n is 4 to 10.

[0054] As described above, the magnetostrictive member of this embodiment is a plurality of magnetostrictive members obtained from the same crystal. It is composed of a crystal of an iron-based alloy with magnetostrictive properties and is a plate-shaped body having a long side and a short side. At least one of the surface and back sides of the plate-shaped body has a plurality of grooves extending along the long side. The ratio (standard deviation / average value) of the standard deviation of the optimal magnetic field strength obtained by electromechanical equivalent circuit analysis of the plurality of magnetostrictive members to the average value of the optimal magnetic field strength is 0.2 or less. With the above-described configuration, the magnetostrictive member of this embodiment exhibits high output and suppresses deviations in the optimal magnetic field strength when manufacturing a magnetostrictive vibration power generation device using magnetostrictive members with high parallel magnetostriction and small deviations in parallel magnetostriction between members. Furthermore, from the viewpoint of suppressing deviations in the optimal magnetic field strength, it is preferable to obtain multiple magnetostrictive members under the same manufacturing conditions, and more preferably to obtain multiple members at once under the same manufacturing conditions.

[0055] (Manufacturing method of magnetostrictive components) Next, the manufacturing method of the magnetostrictive member of this embodiment will be described. The manufacturing method of the magnetostrictive member of this embodiment is the manufacturing method of the magnetostrictive member 1 of this embodiment described above. The manufacturing method of the magnetostrictive member of this embodiment, which is the manufacturing method of the magnetostrictive member 1 of this embodiment described above, includes: forming a plurality of grooves 2 extending along the long side direction D1 on at least one of the surface 3 and the back surface 4 of a plate-shaped body made of a crystal of an iron-based alloy having magnetostrictive properties and having a long side direction D1 and a short side direction D2; and performing heat treatment on the plate-shaped body on which the plurality of grooves extending along the long side direction are formed.

[0056] Furthermore, in the following description, a method for manufacturing the magnetostrictive member 1 from a single crystal ingot of Fe-Ga alloy will be described as an example, but the manufacturing method of the magnetostrictive member in this embodiment is not limited to the following description. Additionally, the content described in this specification that can be applied to the manufacturing method of the magnetostrictive member in this embodiment also applies to the manufacturing method of the magnetostrictive member in this embodiment. Furthermore, in the following manufacturing method of the magnetostrictive member in this embodiment, the content applicable to the magnetostrictive member of this embodiment described above also applies to the magnetostrictive member of this embodiment.

[0057] Figure 5 This is a flowchart illustrating an example of a method for manufacturing a magnetostrictive member according to this embodiment. Figure 6 The figures show the first to third examples (a, b, c) of single crystal (single crystal ingot) and thin plate components. The manufacturing method of the magnetostrictive component in this embodiment includes, for example, a crystal preparation process (step S1), a crystal cutting process (step S2), a groove forming process (step S3), a cutting process (step S4), and a heat treatment process (step S5).

[0058] In the manufacturing method of the magnetostrictive component according to this embodiment, firstly, in the crystal preparation step (step S1), a crystal of an iron-based alloy having magnetostrictive properties is prepared. The prepared crystal can be a single crystal or a polycrystalline crystal. Furthermore, the prepared crystal can be a cultivated crystal or a commercially available product. For example, in the crystal preparation step, a single crystal of an Fe-Ga alloy is prepared. The cultivation method for the Fe-Ga alloy single crystal is not particularly limited. The cultivation method for the Fe-Ga alloy single crystal can be, for example, the Czochralski method, unidirectional solidification method, etc. For example, the Cz method can be used in the Czochralski method, and the VB method, VGF method, and micro-pull-down method can be used in the unidirectional solidification method.

[0059] The magnetostriction constant of Fe-Ga alloy single crystals is maximized by setting the gallium content to 18.5 at% or 27.5 at%. Therefore, the gallium content of Fe-Ga single crystals is preferably 16.0~20.0 at% or 25.0~29.0 at%, more preferably 17.0~19.0 at% or 26.0~28.0 at%. The shape of the grown single crystal is not particularly limited, for example, it can be cylindrical or prismatic. In addition, the grown single crystal can be cut off as needed using a cutting device to cut off the seed crystal, the diameter-enlarged portion, or the shoulder (the portion that increases from the seed crystal to the predetermined diameter of the single crystal), thereby producing a cylindrical single crystal. The size of the grown single crystal is not particularly limited as long as it can ensure the size of the magnetostrictive member in the predetermined direction. In the case of growing Fe-Ga single crystals, a seed crystal with the top or bottom surface of the seed crystal processed into a {100} face in a manner with the growing axis direction <100> is used for growing. The Fe-Ga alloy single crystals are grown in a direction perpendicular to the top or bottom surface of the seed crystal, and inherit the orientation of the seed crystal.

[0060] After the crystal preparation process (step S1), a crystal cutting process (step S2) is performed. The crystal cutting process is a process of cutting the crystal to produce a thin sheet component. The thin sheet component is a component made of the material that becomes the magnetostrictive component 1 of this embodiment. The crystal cutting process is, for example, a process of using a cutting device to cut a single crystal of Fe-Ga alloy with magnetostrictive properties to produce a thin sheet component with the {100} plane as the main surface. The cutting device can be a wire EDM machine, an internal cutting device, a wire saw, etc. Among them, it is particularly preferred to use a multi-wire saw, which can cut multiple thin sheet components at the same time. In the case of Fe-Ga single crystal, the cutting direction of the single crystal is <100>, and the cutting is performed with the cutting surface, that is, the main surface of the thin sheet component, as the {100} plane. The cutting direction of the single crystal is not particularly limited. The cutting direction of the single crystal is, for example, as follows: Figure 4 As shown, the direction of growth of the single crystal (the direction in which the crystal is grown) can be either perpendicular or parallel.

[0061] After the crystal cutting process (step S2), a groove forming process (step S3) is performed. In the groove forming process, a plurality of grooves 2 are formed on at least one of the surface 3 and the back surface 4 of the obtained sheet metal member. In the groove forming process, by appropriately adjusting the configuration of the plurality of grooves 2 formed on the magnetostrictive member, a material of a magnetostrictive member having magnetostrictive properties such as the force coefficient of this embodiment can be obtained. The plurality of grooves 2 can stabilize the magnetostrictive constant, the parallel magnetostriction amount, and the force coefficient at a high level, thereby modifying the magnetostrictive properties such as the magnetostrictive constant, the parallel magnetostriction amount, and the force coefficient. In the groove forming process, a plurality of grooves 2 are formed on the sheet metal member in such a way that when the sheet metal member is finally cut to form the magnetostrictive member 1, a plurality of grooves 2 extending in the long side direction D1 of the magnetostrictive member 1 are formed. For example, a plurality of grooves 2 can be formed by performing surface grinding on at least one of the surface and back surfaces of the sheet metal member obtained by the crystal cutting process. Hereinafter, an example of performing the groove forming process by surface grinding of the sheet metal member will be described. When multiple grooves 2 are formed by surface grinding, the modification effect of the magnetostrictive properties such as the magnetostrictive constant, parallel magnetostriction, and force coefficient can be effectively realized. That is, in this embodiment, the magnetostrictive member 1 preferably has at least one of the surface and back surfaces of the plate-like body having a unidirectional machining surface with the long side direction as the machining direction.

[0062] Surface grinding is performed using a surface grinder. In surface grinding, from the viewpoint of effectively reflecting the effects of the modification of the magnetostriction constant and the amount of parallel magnetostriction, it is preferable that the direction of the grinding marks formed on the thin sheet member is parallel to the long side direction D1 of the magnetostrictive member 1. For this reason, the grinding marks are preferably straight. When making the grinding marks straight, the surface grinder is preferably one in which the movement direction of the grinding wheel or the machining table is linear; a surface grinder using a flat grinding wheel and a reciprocating motion of the machining table is preferred. Alternatively, a surface grinder using a cup-shaped grinding wheel and a rotating machining table can be used, but when using such a surface grinder, since the grinding marks are curved, it is preferable to set the grinding marks to have a small curvature (small degree of bending).

[0063] Furthermore, the aforementioned grinding marks need to be formed on the surface of the magnetostrictive member 1. Therefore, when processing is performed due to thickness adjustment of the thin sheet member, etc., surface grinding can be performed after the predetermined processing is completed using a processing machine other than a surface grinder, such as a double-sided polishing device or a surface grinder using a cup-shaped grinding wheel. Alternatively, surface grinding can be performed after the surface of the thin sheet member (magnetostrictive member) is polished to a mirror finish by grinding as before. From the viewpoint of effectively reflecting the effects of the aforementioned modification of the magnetostriction constant and the amount of parallel magnetostriction, it is preferable to perform surface grinding on both the front and back surfaces of the thin sheet member.

[0064] For grinding wheels used in surface grinding, the lower limit of the roughness (grit size) of the grinding wheel is preferably #40 or higher, more preferably #100 or higher, and the upper limit is preferably #500 or lower, more preferably #400 or lower. The range is preferably #40 or higher and #500 or lower, more preferably #40 or higher and #400 or lower, and even more preferably #100 or higher and #400 or lower. When the roughness (grit size) of the grinding wheel is within the above range, the modification effect of the magnetostrictive constant and the amount of parallel magnetostriction can be more reliably exerted. In addition, when a grinding wheel smaller than #40 is used, the size of the grinding marks is sometimes unstable. If a grinding wheel larger than #500 is used, the surface of the magnetostrictive component becomes smooth, and there is a risk that the modification effect of the magnetostrictive constant and the amount of parallel magnetostriction cannot be effectively manifested.

[0065] In the groove forming process, for example, the plurality of grooves 2 are preferably formed such that the surface roughness Ra of the long side direction D1 of the surface on which the plurality of grooves 2 are formed in the magnetostrictive member 1 is within a predetermined range. For example, the plurality of grooves 2 are preferably formed such that the lower limit of the surface roughness Ra of the long side direction D1 of the surface on which the plurality of grooves 2 are formed is preferably 0.3 μm or more, the upper limit is preferably 1.5 μm or less, and the range is 0.3 μm or more and 1.5 μm or less. In addition, the plurality of grooves 2 are preferably formed such that the lower limit of the surface roughness Ra of the short side direction D2 of the surface on which the plurality of grooves 2 are formed in the magnetostrictive member 1 is preferably 0.6 μm or more, more preferably 0.7 μm or more, the lower limit is preferably 4.5 μm or less, and the range is preferably 0.6 μm or more and 4.5 μm or less. In addition, the plurality of grooves 2 are preferably formed such that the magnetostriction constant and the amount of parallel magnetostriction in the magnetostrictive member 1 and the magnetostrictive material used as the material of the magnetostrictive member 1 are within a predetermined range. For example, the plurality of grooves 2 are preferably formed such that the magnetostrictive constant of the magnetostrictive member 1 and the magnetostrictive material is 200 ppm or more and the parallel magnetostriction amount is 200 ppm or more. The plurality of grooves 2 within the range of the preferred surface roughness Ra, magnetostrictive constant, and parallel magnetostriction amount described above can be formed by the aforementioned surface grinding process. Furthermore, as long as the plurality of grooves 2 can be formed on at least one of the surface 3 and the back surface 4 of the obtained sheet metal member, the groove forming process can also be performed by methods other than surface grinding. For example, the sheet metal member can also be manufactured by forming the plurality of grooves 2 using a wire saw with a fixed abrasive grain. That is, the grooves formed when slicing crystals using a wire saw with a fixed abrasive grain can also be used as the plurality of grooves 2. In wire sawing, there are two methods: free abrasive method and fixed abrasive method. The free abrasive method involves pressing the workpiece against multiple parallel rows of extremely fine wires spaced at a certain interval. While feeding the wires along their direction, a processing fluid containing abrasive grains (also called abrasive slurry) is supplied between the workpiece and the wires, thereby performing the cut. The fixed abrasive method involves feeding a wire with abrasive grains such as diamond fixed by electrodeposition or an adhesive along its direction while cutting the workpiece. The cut surface of the free abrasive method results in a non-directional pear-skin texture, which does not achieve the effects of this invention. However, when cutting with a wire saw using the fixed abrasive method, grinding marks are generated in the wire feed direction, allowing the formation of multiple grooves 2 similar to those in the aforementioned planar grinding process. Furthermore, when cutting with a wire saw using the fixed abrasive method, the crystal cutting process (step S2) and the groove forming process (step S3) can be shared, enabling efficient production of thin sheet components. Alternatively, multiple grooves 2 can also be formed by applying pressure using sandpaper or the like. In the groove forming process, by appropriately adjusting the configuration of the multiple grooves 2 formed on the magnetostrictive member, it is possible to obtain a magnetostrictive member material having the force coefficient and the like of this embodiment.For example, as described above, in this embodiment, the magnetostrictive properties, including optimal magnetic field strength and force coefficient, are sometimes affected by the width, length, and thickness of the magnetostrictive member. However, through the groove forming process, the configuration of the plurality of grooves 2 formed on the magnetostrictive member is appropriately adjusted according to the width, length, and thickness of the magnetostrictive member, thereby obtaining a magnetostrictive member with adjusted (modified) magnetostrictive properties and having the force coefficient, etc., of this embodiment. The configuration (conditions) of the plurality of grooves 2 formed on the magnetostrictive member of this embodiment can be set through preliminary experiments.

[0066] After the groove forming process (step S3), a cutting process (step S4) is performed. The cutting process is a process of cutting the thin plate member with multiple grooves 2 formed by the groove forming process to obtain the magnetostrictive material. This magnetostrictive material becomes the material of the magnetostrictive member 1 of this embodiment. By performing heat treatment on the magnetostrictive material in the heat treatment process described later, the magnetostrictive member 1 of this embodiment can be obtained.

[0067] In the cutting process, when cutting the thin plate component with multiple grooves 2, the thin plate component is cut in such a way that multiple grooves 2 extending along the long side direction D1 are formed in the finally manufactured magnetostrictive component 1. In the cutting process, the thin plate component is cut to a predetermined size. In the cutting process, the thin plate component is cut as magnetostrictive material, for example, so that the magnetostrictive component 1 appears as a rectangular plate when viewed from above. In the cutting process, the thin plate component is cut using a cutting device. The cutting device used in the cutting process is not particularly limited; for example, a peripheral cutting device, a wire EDM machine, a wire saw, etc., can be used. The direction in which the magnetostrictive material is collected from the thin plate component is not particularly limited; for example, it can be set to a direction that allows for more efficient acquisition of the size of the magnetostrictive component, etc.

[0068] Finally, a heat treatment process (step S5) is performed. This heat treatment process further reduces the optimal magnetic field strength of the magnetostrictive member while maintaining a high force coefficient, and also reduces deviations. It is presumably because the internal stress on the surface and back of the magnetostrictive member is alleviated through heat treatment. For example, in the heat treatment process, multiple grooves 2 extending along the long side direction D1 are formed on the surface and back of the magnetostrictive material obtained from the cutting process, and the magnetostrictive material is heat-treated at a predetermined temperature and time. This heat treatment modifies the ratio (standard deviation / average value) of the optimal magnetic field strength obtained through electromechanical equivalent circuit analysis of the magnetostrictive member to 0.2 or less. Furthermore, the heat treatment modifies the ratio (standard deviation) of the force coefficient deviation to the average value to 0.3 or less. Additionally, the heat treatment modifies the average value of the optimal magnetic field strength and the average value of the force coefficient to the aforementioned ranges. Through this heat treatment, the magnetostrictive member 1 of this embodiment can be obtained. Furthermore, the effect of further reducing the optimal magnetic field strength of the magnetostrictive component and decreasing the deviation while maintaining a high force coefficient based on heat treatment is also effective in materials without multiple slots 2.

[0069] The heat treatment method is not particularly limited. For example, box-shaped or tubular electric furnaces can be used. The heating temperature is not particularly limited as long as it exhibits the effects of the heat treatment described above. Furthermore, the heat treatment conditions (temperature and time) can be obtained through preliminary experiments. The heating temperature (heat treatment temperature) is preferably 400°C or higher and 700°C or lower, more preferably 600°C or higher and 650°C or lower. When the heat treatment temperature is lower than 400°C, the internal stress cannot be alleviated by heat treatment due to the low temperature, and therefore the optimal magnetic field strength sometimes does not change. In addition, when the heat treatment temperature is higher than 700°C, the temperature is too high, so the grinding effect due to heat treatment is weakened, the parallel magnetostriction decreases, and the force coefficient also decreases. If the heat treatment temperature is within the above temperature range, the average value of the optimal magnetic field strength of the magnetostrictive component can be further reduced.

[0070] The holding time of the heat treatment is preferably 5 hours or less, more preferably 30 minutes or more and 5 hours or less, and even more preferably 30 minutes or more and 1 hour [1]. If it is within the above range, the effect of suppressing the deviation of the magnetostrictive component can be more reliably exerted.

[0071] Furthermore, the atmosphere used in heat treatment is preferably a non-reactive gas atmosphere. For example, argon or nitrogen can be used. By using a non-reactive gas atmosphere, oxidation of the surface of the magnetostrictive component can be prevented. In addition, the non-reactive gas can be continuously supplied to the heat treatment furnace. Regarding the flow rate, although it also depends on the heat treatment furnace, it is preferably 0.5 to 5 L / h when the non-reactive gas is argon.

[0072] Furthermore, if the heat treatment process (step S5) is performed without the groove forming process (step S3), the internal stress is relieved and the deviation of the optimal magnetic field strength is reduced, but the force coefficient remains unchanged, the average value is low, and the deviation remains large.

[0073] Furthermore, in the example above, in the cutting process (step 4), a heat treatment process (step S5) is performed after the part is cut into the shape of a magnetostrictive member. However, in the present invention, the heat treatment process (step S5) may be performed after the groove forming process (step S3), followed by the cutting process (step S4).

[0074] Furthermore, such as Figure 7 As shown, a secondary groove forming process (step S6) can also be performed after the heat treatment process (step S5) to additionally form multiple grooves 2 extending along the long side on the heat-treated plate. For example, the secondary groove forming process (step S6) can be performed by forming the same grooves as in the above-described groove forming process (step S3). The force coefficient is maintained by the secondary groove forming process (step S6). There is also a case where the average value of the optimal magnetic field strength increases, but the deviation of the optimal magnetic field strength is maintained. The lower the optimal magnetic field strength, the better, so it is preferable not to perform the secondary groove forming process (step S6), but it can be used to adjust the optimal magnetic field strength. Furthermore, the grooves 2 formed in the secondary groove forming process (step S6) can be formed under the same conditions as in the groove forming process (step S3), or they can be formed under different conditions than in the groove forming process (step S3). That is, the shape, amount, and other configuration of the grooves formed in the secondary groove forming process (step S6) can also be different from the grooves 2 formed in the groove forming process (step S3).

[0075] Example The following description uses embodiments of the present invention, but the present invention is not limited to these embodiments in any way.

[0076] [Example 1] The magnetostrictive component is manufactured based on the manufacturing method of this embodiment described above. The raw materials are adjusted to an iron-gallium ratio of 81:19 (stoichiometric ratio) to prepare cylindrical Fe-Ga alloy single crystals grown using the vertical Bridgman (VB) method (crystal preparation step, S1). The growth axis direction of the single crystal is set as... <100> The orientation of the {100} planes on the upper or lower surface of the single crystal perpendicular to the crystal growth axis was confirmed by X-ray diffraction. Furthermore, samples from the upper and lower surfaces of the crystal were measured using a Shimadzu sequential plasmaluminescence analyzer (ICPS-8100), and the gallium content, as a concentration of the single crystal, was found to be 17.2–19.8 at.

[0077] As described below, magnetostrictive components are manufactured from cultivated single crystals. First, a free abrasive wire saw is used in a direction parallel to the single crystal cultivation direction (and...). <100> The single crystal is cut along the orientation parallel to the surface to create a thin plate component with a cut surface, i.e., the main surface, of {100} (crystal cutting process, step S2). Next, the obtained thin plate component is subjected to surface grinding using a #200 flat grinding wheel on a surface grinder to adjust the thickness of the thin plate component and to form multiple grooves (grinding marks) on the front and back surfaces in order to obtain the magnetostrictive component of this embodiment described above (groove forming process, step S3). Then, the cutting position is set so that the long side direction of the magnetostrictive component is the same as the grinding direction during surface grinding, i.e., the grinding mark direction, and a magnetostrictive material with a long side dimension of 16mm × a short side dimension of 4mm × a thickness of 0.5mm is cut out using an external cutting edge device (magnetostrictive component before heat treatment) (cutting process, step S4).

[0078] Next, the magnetostrictive properties of the cut magnetostrictive material were measured. The magnetostrictive properties were measured using the methods described above. Figure 4 The impedance measuring device shown was used to measure the impedance and determine the force coefficient and the optimal magnetic field strength. In addition, the impedance measurement was performed as follows. A measuring coil was made by cutting out a 16×4×0.5mm magnetostrictive member and inserting the magnetostrictive member [2], and the impedance measurement was performed in the same manner as in Patent Document 7. The excitation current was set to 10~70mA and applied at 5mA intervals. When converted to magnetic field strength, 1mA=78.4A / m, and a bias magnetic field was applied at 0.392kA / m intervals in the range of 0.784~5.488kA / m. The impedance was measured using an impedance analyzer at a frequency of 50~150kHz, and the force coefficient α was calculated for each magnetic field strength. The optimal magnetic field strength with the maximum force coefficient α and the force coefficient αmax at this time were calculated.

[0079] In addition, ten of the above magnetostrictive materials were fabricated, and the force coefficient and optimal magnetic field strength were determined using the same method. The average value and deviation (standard deviation) of each material were calculated. The results are summarized in Table 1.

[0080] Next, the ten magnetostrictive materials cut out as described above are subjected to heat treatment. A tubular electric furnace is used for the heat treatment. Argon gas is circulated in the furnace at a rate of 1 L / min. The heat treatment is carried out at a temperature of 600°C and a holding time of 1 hour. The magnetostrictive component is obtained through heat treatment (heat treatment process, step S5).

[0081] Subsequently, the force coefficient and optimal magnetic field strength of the magnetostrictive components were measured. The results are shown in Table 1. Furthermore, Table 1 shows the average value (AVE) and deviation (standard deviation σ) of ten magnetostrictive components. Additionally, regarding the force coefficient and optimal magnetic field strength, the ratio of deviation (standard deviation) to average value (standard deviation σ / average value AVE), the average value and deviation (standard deviation) of the optimal magnetic field strength, and the ratio of their values ​​before and after heat treatment (after heat treatment / before heat treatment) were calculated and shown in Table 1.

[0082] [Example 2, Example 3] Examples 2 and 3 are comparative examples of changing the heating temperature and holding time of the heat treatment of the magnetostrictive component.

[0083] Example 2: The holding time for the heat treatment of the magnetostrictive component was set to 5 hours. Except as described above, it was the same as Example 1. Example 3: The heating temperature for the heat treatment was set to 450°C. Except as described above, it was the same as Example 1. The respective manufacturing conditions and evaluation results are shown in Table 1.

[0084] [Example 4] In Example 4, except that the thickness was changed from 0.5 mm to 0.6 mm, steps S1 to S5 were performed in the same manner as in Example 1. A magnetostrictive material with a long side dimension of 16 mm × a short side dimension of 4 mm × a thickness of 0.6 mm was produced. Then, as a second groove forming process (step S6), a surface grinder was used with a #200 flat grinding wheel to perform surface grinding, forming multiple grooves (grinding marks) on both the surface and back surfaces. In the second groove forming process (step S6), the long side direction of the magnetostrictive component with the multiple grooves (grinding marks) is the same as the grinding direction during surface grinding, i.e., the grinding mark direction. The manufacturing conditions and evaluation results are shown in Table 1. Furthermore, the values ​​in the table after heat treatment are the values ​​after heat treatment and second groove forming.

[0085] [Comparative Example 1, Comparative Example 2] In Comparative Example 1, the surface of the magnetostrictive material was designed as a machined surface (wire saw machined surface) formed by cutting with a wire saw device using a processing fluid containing abrasive particles to cut free abrasive particles. No multiple grooves 2 were formed on the wire-machined surface. Except as described above, it was the same as in Example 1. In Comparative Example 2, the heat treatment holding time for the magnetostrictive material was set to 5 hours. Except as described above, it was the same as in Comparative Example 1. The manufacturing conditions and evaluation results are shown in Table 1.

[0086] [Example 5] Compared with Example 1, Example 5 increased the size of the magnetostrictive component by changing its dimensions to 32mm in the long side direction, 8mm in the short side direction, and 1mm in thickness. In the groove forming process (step S3), a #80 flat grinding wheel was used for surface grinding. The heat treatment holding time of the magnetostrictive material was changed to 2 hours for comparison. The manufacturing conditions and evaluation results are shown in Table 1.

[0087] [Example 6] Compared to Example 1, Example 6 increased the size of the magnetostrictive component by changing its dimensions to 64mm in the long side direction, 16mm in the short side direction, and 2mm in thickness. In the groove forming process (step S3), a #40 flat grinding wheel was used for surface grinding. The heat treatment holding time of the magnetostrictive material was also changed to 2 hours. The manufacturing conditions and evaluation results are shown in Table 1.

[0088] [Example 7] Compared to Example 1, Example 7 increased the size of the magnetostrictive component by changing its dimensions to 96mm in the long side direction, 24mm in the short side direction, and 3mm in thickness. In the groove forming process (step S3), a #40 flat grinding wheel was used for surface grinding. The heat treatment holding time of the magnetostrictive material was also changed to 3 hours. The manufacturing conditions and evaluation results are shown in Table 1.

[0089]

[0090] [Summarize] Based on the results of the above embodiments, in Examples 1-3, the average value and deviation of the optimal magnetic field strength after heat treatment were smaller compared to before heat treatment. In Example 4, the deviation of the optimal magnetic field strength was smaller compared to before heat treatment. The average value of the optimal magnetic field strength was larger compared to before heat treatment. In Examples 1-4, the ratio of the deviation of the optimal magnetic field strength before and after heat treatment (σ after heat treatment / σ before heat treatment) was less than 0.3, indicating that by performing heat treatment, the deviation of the optimal magnetic field strength was reduced, achieving homogenization. In addition, in Examples 1-4, the force coefficient changed little before and after heat treatment, remaining stable and good at a high level. Compared to Examples 1-4, in Comparative Examples 1 and 2, the surface condition of the magnetostrictive component was a wire saw-machined surface, resulting in a large deviation of the force coefficient, which did not change significantly before and after heat treatment. In addition, in Examples 1-6, the force coefficient was equal before and after heat treatment, and even without heat treatment, the force coefficient remained stable at a high level. Furthermore, it was found that in Examples 5-7, the average value of the force coefficient was larger compared to Examples 1-4. Furthermore, in Example 7, compared to Examples 1-6, the average force coefficient before heat treatment was lower and the deviation was larger. In Example 7, the thickness was 3 mm, and the thickness of the magnetostrictive member was greater than 2 mm. It is estimated that the modification effect of the aforementioned magnetostrictive properties brought about by forming multiple grooves 2 extending along the long side direction D1 of the magnetostrictive member was smaller than that when the thickness was less than 2 mm. In addition, in Examples 5-7, compared to Examples 1-4, it is estimated that the dimensions in the long side direction and the dimensions in the short side direction also affected the force coefficient. It can be seen that in the case of Example 7, by performing heat treatment after forming multiple grooves 2 extending along the long side direction D1 of the magnetostrictive member, it is possible to obtain a modification effect that is approximately the same as that when the thickness is less than 2 mm. Therefore, it can be seen that even a magnetostrictive member with a thickness greater than 2 mm can obtain a force coefficient that is stable at a high level. Based on the results of the examples, it can be confirmed that the magnetostrictive member 1 of this embodiment has the characteristics of high force coefficient, small deviation between members, and further reduced optimal magnetic field strength with small deviation. Furthermore, based on the results of the embodiments, it can be confirmed that the manufacturing method of the magnetostrictive component according to the present invention can easily manufacture magnetostrictive components with high force coefficient, small deviation between components, and small deviation while reducing the optimal magnetic field strength.

[0091] Furthermore, the technical scope of the present invention is not limited to the methods described in the above embodiments, etc. One or more of the elements described in the above embodiments, etc., are sometimes omitted. Additionally, the elements described in the above embodiments, etc., can be appropriately combined. Furthermore, wherever permitted by law, the disclosures of Japanese Patent Application No. 2023-037128 and all documents cited in the above embodiments, etc., are incorporated into this description.

[0092] For example, in the above description, an example of a magnetostrictive member having multiple grooves 2 extending along the long side direction on at least one of the surface and back sides of a plate-like body was described, but the multiple grooves 2 may not be present. For example, it may be configured such that multiple magnetostrictive members are obtained from the same crystal, composed of a crystal of an iron-based alloy having magnetostrictive properties, and are plate-like bodies having a long side direction and a short side direction. The ratio of the standard deviation to the average value of the optimal magnetic field strength obtained by electromechanical equivalent circuit analysis of the multiple magnetostrictive members (standard deviation / average value) is 0.2 or less, and the ratio of the standard deviation to the average value of the force coefficient obtained by electromechanical equivalent circuit analysis (standard deviation / average value) is 0.3 or less. In this configuration, when using a magnetostrictive member with high parallel magnetostriction and small deviation in parallel magnetostriction between members to manufacture a magnetostrictive vibration power generation device, the device output is large, and even if the optimal magnetic field strength is further reduced, deviation can be suppressed. This magnetostrictive member can be obtained, for example, by modifying the ratio (standard deviation / average value) of the optimal magnetic field strength obtained by analyzing the magnetostrictive member through electromechanical equivalent circuit based on the above-mentioned heat treatment.

[0093] Explanation of reference numerals in the attached figures 1: Magnetostrictive components; 2: slot; 3: Surface; 4: Back side; D1: Long side direction; D2: Short side direction; S1: Crystal preparation process; S2: Crystal cutting process; S3: Groove forming process; S4: Cutting process; S5: Heat treatment process; S6: Secondary tank forming process.

Claims

1. A magnetostrictive component, wherein, The magnetostrictive component is obtained by producing multiple magnetostrictive components from the same crystal. It is composed of crystals of iron-based alloys with magnetostrictive properties. It is a plate-shaped body with both a long side and a short side. At least one of the surface and back surfaces of the plate-like body has a plurality of grooves extending along the long side direction. The ratio of the standard deviation of the optimal magnetic field strength obtained by electromechanical equivalent circuit analysis of the plurality of magnetostrictive components to the average value of the optimal magnetic field strength (standard deviation / average value) is less than 0.

2.

2. The magnetostrictive member according to claim 1, wherein, The ratio of the standard deviation to the average value of the force coefficients obtained by analyzing the electromechanical equivalent circuit of the plurality of magnetostrictive components (standard deviation / average value) is less than 0.

3.

3. The magnetostrictive member according to claim 1, wherein, The ratio of the standard deviation to the average value of the force coefficients obtained by analyzing the electromechanical equivalent circuit of the plurality of magnetostrictive components (standard deviation / average value) is less than 0.

1.

4. A magnetostrictive component, wherein, The magnetostrictive component is obtained by producing multiple magnetostrictive components from the same crystal. It is composed of crystals of iron-based alloys with magnetostrictive properties. It is a plate-shaped body with both a long side and a short side. The ratio of the standard deviation to the average value of the optimal magnetic field strength obtained by electromechanical equivalent circuit analysis of the plurality of magnetostrictive components (standard deviation / average value) is less than 0.2, and the ratio of the standard deviation to the average value of the force coefficient obtained by electromechanical equivalent circuit analysis (standard deviation / average value) is less than 0.

3.

5. The magnetostrictive member according to any one of claims 1 to 4, wherein, The thickness of the plate-like body is 0.3 mm or more and 5 mm or less.

6. A method for manufacturing a magnetostrictive component, as described in any one of claims 1 to 4, wherein, The method for manufacturing the magnetostrictive component includes: A plurality of grooves extending along the long side direction are formed on at least one of the surface and back surfaces of a plate-like body composed of ferroalloy crystals with magnetostrictive properties; and The plate-shaped body having a plurality of grooves extending along the long side is subjected to heat treatment.

7. The method for manufacturing a magnetostrictive component according to claim 6, wherein, The method for manufacturing the magnetostrictive member includes forming the plurality of grooves by surface grinding.

8. The method for manufacturing a magnetostrictive component according to claim 6, wherein, The heat treatment temperature is above 400℃ and below 700℃.

9. The method for manufacturing a magnetostrictive component according to claim 6, wherein, The heat treatment duration is no more than 5 hours.

10. The method for manufacturing a magnetostrictive component according to claim 6, wherein, The method for manufacturing the magnetostrictive member includes forming a plurality of grooves extending along the long side on the heat-treated plate.

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